1. Field of the Invention
This invention is concerned with the provision of assistance to vehicle drivers in aligning a towing or tractor vehicle with a trailer to be attached thereto.
2. Description of the Prior Art
There are many forms of attachments for connecting trailers to towing vehicles, but one for which the invention is particularly, though not exclusively, intended is that in which an upwardly directed ball is mounted at the rear of the towing vehicle and a downwardly directed socket is mounted at the front of the trailer. The socket is usually at the forward end of a towbar projecting from the trailer and the ball is usually projecting behind the rear bumper of the towing vehicle. In the case of a lightweight trailer with one axle, it is possible to lift the front of the trailer by the towbar and manoeuvre the trailer until the socket is over the ball and can be lowered onto it and attached thereto. However, in the case of close-coupled twin axle trailers, this is not so easy and a jockey wheel of adjustable height is often provided on the towbar, by which the height of the towbar can be adjusted so that the socket clears the ball for detachment and attachment. The jockey wheel can also be used to lift the front of the trailer, so that one of the pairs of wheels is lifted clear of the ground to make manoeuvring easier. Nevertheless, with heavy loads in the trailer, such as horses, boats of the contents of a caravan, it is much easier to leave the trailer at the point of detachment and to reverse the towing vehicle into position with the ball under the socket when attachment is again required.
However, it is still not easy to reverse the towing vehicle exactly into the position required to within a few centimeters. This is particularly the case when the driver of the towing vehicle is trying to attempt the manoeuvre alone. It may not be so difficult to align the towing vehicle in the lateral direction, though experience suggests that even this may require several attempts. But in order to place the ball exactly under the socket, it is necessary to align the vehicle with the trailer in the fore-and-aft direction. Without being able to see the ball or socket, as they are too low in most cases, this is very difficult.
By the invention, the alignment of a towing vehicle with a trailer in the lateral and/or fore-and-aft direction is rendered much easier.